Releasable connection arrangement for two rotationally symmetrical components

ABSTRACT

A releasable connection arrangement that includes, a first component, which has a collar projecting radially outwards with a first clamping surface and a first bearing surface and a socket disposed at an open end of a second component for retaining the collar by gripping round it axially. A second bearing surface is formed in the socket to co-operate with the first bearing surface. A groove is formed either in the first or in the second bearing surface to receive a seal. A second clamping surface is formed in the socket at an axial distance from the second bearing surface in which a number of ring wedge-shaped tensioning members which are distributed over the circumference and are disposed such that first wedge surfaces abut the first clamping surface and second wedge surfaces abut the second clamping surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to DE 102004013332.8 filed Mar. 17,2004.

TECHNICAL FIELD

The invention relates to a releasable connection arrangement, with anon-positive and positive fit, for two rotationally symmetricalcomponents at a connection point, especially for creating a leak-proofconnection between closure elements on power plant valves. A connectionarrangement of this kind is known, for example, from the German UtilityModel DE 298 22 922 U1.

BACKGROUND OF THE INVENTION

In the known connection arrangement, each tensioning member has theforce of a straining screw acting directly upon it, the screw actingbetween the tensioning members and one shoulder of the first componentand bracing the tensioning member like a wedge along the wedge surfacesbetween the components.

While a connection arrangement of this kind is beneficial from the pointof view of the frictional contact connection, it nevertheless possessesthe disadvantage that for installation or dismantling purposes, numerousstraining screws have to be tightened evenly, which takes a relativelygreat amount of time. Uneven torque can lead to damage in operation.Apart from that, it is time-consuming and expensive to produce thenumerous counter-bearings needed for the straining screws.

The invention has set itself the objective of improving a connectionarrangement of the generic kind, especially with regard to thedisadvantages described above.

BRIEF SUMMARY OF THE INVENTION

The invention achieves this objective by means of a connectionarrangement of the generic kind characterized in that an expanding ringis provided, abutting third wedge surfaces of the tensioning memberswith an outer expanding surface, and tensioning means are provided,acting between the expanding ring and one of the components, with whichthe expanding ring can be moved axially and the tensioning members canbe moved radially or radially/axially.

Thanks to the arrangement in accordance with the invention, with anexpanding ring distributing the tensioning forces of the tensioningmeans over the circumference, fewer or different tensioning means can beprovided than is the case in the state of the art, so that assembly ordismantling can be performed more easily and more quickly. Apart fromthat the flow of forces through the connection can be improved stillfurther.

It is preferably provided that the first and second bearing surfaces runradially. The groove can be formed in part of a radial portion of thefirst or second bearing surface so as to arrange the seal in parallel tothe bearing surface proper.

It is preferably provided that the first clamping surface should includea wedge angle with the second clamping surface, which is matched to acone angle of the outer expanding surface in such a way that theexpanding ring causes self-locking bracing of the components.

It can be provided that the first clamping surface runs radially and thesecond clamping surface runs conically.

Alternatively, it can be provided that the first clamping surface runsconically and the second clamping surface runs radially.

In a further alternative, it can be provided that the first and secondclamping surfaces run conically.

The expanding ring can be formed continuously in the circumferentialdirection, or alternatively it can be provided that the expanding ringhas radial expansion slots arranged spread out in the circumferentialdirection and a conically formed inner expanding surface with which itabuts a correspondingly conically formed third expanding surfacedisposed on the second component, and that it can be, radially expandedby axial displacement. In this context, it can be provided that theouter expanding surface and the third wedge surfaces of the tensioningmembers are in each case formed axis-cylindrically or conically.

It can be provided that the expansion slots do not extend over an entireaxial length of the expanding ring. Alternatively, the inventionenvisages that the expanding ring is provided with expansion slotsarranged in an alternating way in the circumferential direction, in themanner of a collet.

The expanding ring can be formed from separate expanding membersdisposed spread out over the circumference, and a thrust collar grippinground them.

In a preferred embodiment of the invention, it is provided that there isa retaining ring releasably mounted on the first component, especiallyon the collar, adjacent to the first clamping surface, which retainingring has a retaining surface running substantially axis-cylindricallyand abutting a locking surface, which runs substantiallyaxis-cylindrically, of the tensioning members and preventing thetensioning members and thus the connection arrangement from beingreleased completely when the expanding ring is released.

The tensioning means can be formed as straining screws distributed overthe circumference. The straining screws can be located in a strainingring secured axially to the first component, especially by means of acircumferential groove and a sliding block.

Alternatively, it can be provided that the straining screws engagethrough the expanding ring into the first component, especially into thecollar.

As a further alternative, it can be provided that the expanding ring hasa flange ring formed integrally with it or resting on it, through whichthe straining screws engage in a circumferential portion of the secondcomponent located radially outside the tensioning members.

Finally, it can be provided as an alternative that the tensioning meanscan be formed by a threaded nut acting on the expanding ring andco-operating with an external or internal thread of the first or secondcomponent.

In a preferred embodiment of the invention, it is provided that thetensioning members consist of parts of a ring divided along two parallelsecant planes which can be mounted, in a manner known per se, at mutual(circumferential) distances that are advantageously small compared toparts obtained by radial sections, i.e. they can be inserted between thefirst and second components.

The invention also relates to a set of tensioning members for aconnection arrangement according to the invention, formed from parts ofa ring divided along two parallel secant planes and having first wedgesurfaces formed radially or conically outwardly, second wedge surfacesformed radially or conically outwardly and internal third,axis-cylindrical or conical, wedge surfaces. Whereas the third wedgesurfaces may be formed either axis-cylindrically or conically with anycombination of angles in the first and second wedge surfaces, either thefirst wedge surfaces may be radial and the second wedge surfacesconical, or vice versa, or both may be conical.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained by means of various embodiments,reference being made to a drawing, in which

FIG. 1A shows one side of a longitudinal section view of a cover lock ofa power plant valve with a connection arrangement in accordance with theinvention, and FIG. 1B shows an alternate view of the cover lock,

FIGS. 2 to 9 show further embodiments as variations on the connectionarrangement shown in FIG. 1, and

FIGS. 10 and 10 a show a plan view and a sectional view of an expandingring of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be explained by reference to various embodimentsrelating to a novel cover lock of a power plant valve. In power plantvalves for new conventional fossil-fuel thermal power plants, which aresubject to high stresses, the operating pressures reach up to approx.300 bar, while the operating temperatures can reach levels of 700° C.and more. The service lives of self-sealing graphite cover seals are notadequate in view of the extreme temperatures and pressures of the media.A graphite seal rapidly oxidizes to CO₂ when an operating temperature of500° C. is exceeded, permitting atmospheric oxygen to enter.

At operating temperatures on these levels, it is conceivable to use,among other things, a radially operative, high-temperature-resistantmetal O-ring seal. From the structural point of view, the cover lockwith a metal O-ring seal must be designed in such a way that the metalO-ring is placed in metal-to-metal contact. With conventional flangelocks or self-sealing locks, this sealing method is of only limitedfeasibility or leads to disproportionately large dimensions of thehousing and the lock member, which are not suitable.

The construction of the invention makes it possible to design a coverlock for valves in an advantageous manner such that a metal O-ring sealis located in metal-to-metal contact and the pressure forces occurringcan be absorbed by the twin action of a rotationally symmetrical conesystem. According to the invention, the operating forces are interceptedby positive-locking ring segments provided with a plurality of conicallateral surfaces which are supported outwardly on the housing andinwardly on an expanding ring by means of cone envelope surfaces. If theangle of the cone is selected in the region of self-locking, i.e. thetangent of the angle of incline is smaller than the lowest staticfriction figure to be expected, this ensures that the axial reactionforces acting on the pre-tensioning members (tensioning means in theform of bolts) are small or virtually zero.

Since the advantageous structural design means that only lowpre-tensioning forces are required, which are independent of theoperating pressure, relaxation and material fatigue do not occur in thetensioning means, and the dimensions relative to the magnitude of theforces which can be transmitted remain relatively small compared toconventional flange locks. The favorable flow of forces through thecomponents connected to the twin-action, rotationally symmetrical conesystem generates the lowest possible folding moments and bending momentsand deformations in the housing and cover. In the outer tensioningmembers, which are in the shape of cone segments, mainly shearingstrains occur, whereas in the expanding ring or supporting cone it ismainly tangential strains or, in the case of a slotted expanding ringsupported on the inside, only compressive strains, which are easy tocontrol.

FIGS. 1A-1B shows different embodiments of a connection arrangement ofthe invention, in which a first component, which is rotationallysymmetrical at least at the connection point and is in this case a cover2 of a power plant valve, has a collar 4 projecting radially outwards,on which are formed a first, radial clamping surface 6 and a first,likewise radial, bearing surface 8.

A second component 10, in this case a housing of a power plant valve,which is likewise formed rotationally symmetrical in the region of theconnection point shown at the top in FIG. 1A has at an open end a socket12, which surrounds and axially overlaps the collar 4 of the firstcomponent 2. Formed in the socket 12 in order to co-operate with thefirst bearing surface 8 of the first component 2 there is a secondbearing surface 14 likewise running radially, a groove 16 being formedin a radially inner region of the second bearing surface 14 to receive ametal O-ring seal 18 and a groove 16′ being formed in the first bearingsurface 8, a seal 18′ being positioned in the groove 16′ shown in FIG.1B. The seal 18 is thus arranged in parallel to the bearing surfaceproper when the two components 2, 10 are fitted together and touching.Thus, the main axial forces are transmitted by the bearing surfaces andnot by the seal which is thus subjected to a predetermined amount ofaxial compression.

In the socket 12 there is formed, at an axial distance from the secondbearing surface 14, a hollowed out portion 20 and a second conicalclamping surface 22, which is opposite the first clamping surface 6 ofthe first component 2 when the components 2, 10 are fitted together asshown.

A number of ring wedge-shaped tensioning members 24 are distributed overthe circumference and are disposed with a first cone envelope or wedgesurface 26 abutting the first clamping surface 6 and with a second wedgesurface 28 abutting the second clamping surface 22.

An expanding ring 34 with an outer expanding surface 32 abutting thirdwedge surfaces 30 of the tensioning members 24 is placed in the axialdirection 36 against the tensioning members 24. Tensioning means areprovided between the expanding ring 34 and the first component 2 (cover)in order to move the expanding ring 34 in the axial direction 36 andthus to move the tensioning members 24 along the second clamping surface22, i.e., in the embodiments according to FIGS. 1A-1B, both in the axialdirection 36 and also radially outwards. In the embodiments according toFIGS. 1A-1B, the tensioning means are formed by straining screws 40,which are screwed into threaded holes 42 of a straining ring 44, which,for its part, is supported against a sliding block 48 inserted into acircumferential groove 46 of the first component 2. Because of therelatively low axial forces that have to be applied through thestraining screws 40, neither the circumferential groove 46 nor thesliding block 48 need to be of any great size, unlike a conventionalflange-like connection, in which the straining screws have to absorb theentire compressive force occurring in operation (operating pressuremultiplied by the internal area of the cover). If the wedge and coneangles defined by the wedge surfaces 26, 28, 30 are selected such thatself-locking occurs, the straining screws 40 merely have to apply thetensioning force needed for assembly, whereas no additional load occursin operation, irrespective of the internal or operating pressure. Sincethe compressive forces between the cover and the housing (first andsecond components) are transmitted through compressive and frictionalforces, the actual task of the straining screws 40 is only to immobilizethe connection arrangement in its frictional connection and positivelocking (first component 2, second component 10, tensioning members 24and expanding ring 34), i.e. to prevent the expanding ring 34 fromcoming loose because of the inevitable vibrations, shocks and the likewhich occur in operation.

In the region of the hollowed out portion 20 in the second component 10,holes 50 are inserted on the level of the tensioning members 24, so thatthe tensioning members 24 can be knocked out in the event ofdismantling. Using axial threaded forcing holes and correspondingforcing screws, not shown, the expanding ring 34 can be pressed out ofthe conical inner ring formed by the tensioning members 24. This ensuresthat the connection arrangement can be dismantled with no difficulty.

Essentially, the further embodiments shown in FIGS. 2 to 9 differ fromthe embodiment explained above merely with regard to the design of theexpanding ring 34 and its bracing with different bracing means.

FIG. 2 shows an expanding ring 34 with axial via holes 60, through whichstud bolts 64 are screwed and engage in blind threaded holes 62 in thefirst component 2, the axial bracing of the expanding ring 34 beingachieved by fastening nuts 66. Because of the closed design of theexpanding ring 34, the stud bolts 64 are merely subjected to axialstrain and not to bending.

FIG. 3 shows a variant in which the expanding ring 34 is not formed in acontinuous, or solid, manner in the circumferential direction, butinstead has expansion slots running in the radial direction and spreadout in the circumferential direction, one of which is indicated by 70 inFIG. 3. It is possible for there merely to be expansion slots insertedin an axial direction, e.g. from the lower side, each of which extendsin accordance with the expansion slot indicated by 70 in FIG. 3, oralternatively the expanding ring 34 can formed like a collet, whereinsuccessive expansion slots in the circumferential direction extend fromalternately opposite axial directions into the expanding ring.

In an alternative embodiment, which is not shown, it would also bepossible for the expanding ring to be composed of separate expandingmembers spread out over the circumference.

In all cases, it is appropriate for the expanding ring to be formed witha thrust collar, indicated by 72 in FIG. 3, gripping round theindividual expanding members or the expanding portions subdivided byexpansion slots. The thrust collar can be formed integrally, withexpanding portions separated by expansion slots, or alternatively as aseparate component.

A feature common to all such embodiments according to FIG. 3 is that theexpanding ring 34 not only has an outer expanding surface 32, but inaddition an inner, conical expanding surface 74, which co-operates witha corresponding conically formed third expanding surface 76 on thesecond component 2. When the tensioning means (straining screws 40) aretightened, the thrust collar 72 thus moves in the axial direction 36relative to the first component 2 in the direction of the collar 4,while the inner expanding surfaces 74 of the slotted portion of theexpanding ring 34 move outwards along the third expanding surface 76both in the axial direction 36 and in the radial direction, i.e. thering expands.

Because of the above-mentioned radial expansion movement of the slottedportion of the expanding ring 34, the third wedge surfaces 30—which areshown conically in FIG. 3—of the tensioning members 24 andcorrespondingly also the outer expanding surface 32 of the expandingring 34 could be formed axis-cylindrically, which simplifiesmanufacture.

FIG. 4 shows a variant of the embodiment according to FIGS. 1 and 2, inwhich the expanding ring 34 has a flange portion or flange ring 80formed integrally with it, through which stud bolts 64 are inserted,which for their part engage in blind threaded holes 62 in the secondcomponent 10. As an alternative to the integral embodiment shown, theflange ring 80 could also be formed as a separate ring gripping over theactual expanding ring 34, as will be explained in more detail below inconnection with FIG. 7.

FIG. 5 shows an embodiment in which the tensioning means are formed by athreaded nut 90 acting on the expanding ring 34, the threaded nut 90co-operating with an external thread 92 of the first component 2.Alternatively, the threaded nut 90 could be provided with an externalthread and the second component 10 with an internal thread in an openend portion of the socket 12 adjacent to the second clamping surface 22,with a corresponding axial shortening of the expanding ring 34 or axiallengthening of the second component 10.

FIG. 6 shows a variant in which the expanding ring 34 is formed inaccordance with FIG. 4, though in this case there is additionally aretaining ring 100 fixed to the collar 4 of the first component 2 bymeans of fastening screws 102. The retaining ring 100 has a retainingsurface 104 running axis-cylindrically, with which it abutscorrespondingly formed locking surfaces 106—which runaxis-cylindrically—of the tensioning members 24. The diameter of theretaining surface 104 is in this case selected such that the retainingring 100 can be inserted when the connection arrangement is in itsassembled but unbraced state, without already bracing the tensioningmembers 24, but at the same time such that the tensioning members 24cannot slip out of the hollowed out portion 20 when the retaining ring100 is inserted. In other words, when the fastening nuts 66 aretightened, a radial gap, which is not shown in FIG. 6, appears betweenthe retaining surface 104 and the locking surfaces 106, since thetensioning members 24 are braced radially outwardly. If the fasteningshould come loose in operation, for whatever reason, it is still notpossible for the cover 2 to be pressed out of the socket 12; instead,there may merely be a more or less slight leak in the connection pointin the region of the seal 18, because the tensioning members 24 stillprevent any substantial axial movement of the components 2, 10 relativeto one another.

FIG. 7 shows a combination of the variants according to FIGS. 3 and FIG.4, where a flange ring 80 is formed as a separate part and to a certainextent could also perform the function of a thrust collar, though thisfunction, rather as in FIG. 7, is already performed by the thrust collar72 as part of the expanding ring 34.

FIG. 8 shows a combination of FIGS. 3 and 5, in which, unlike FIG. 3,the tensioning means are formed by a threaded nut 90.

FIG. 9 shows a variant in which the tensioning members 24 do not (each)have, as has been the case so far, a first, radial wedge surface 26 anda second, conical wedge surface 28, but rather a first, conical wedgesurface 26 and a second, radial wedge surface 28. It goes without sayingthat the first clamping surface 6 of the first component 2 correspondsto the second, conical wedge surface 28 and is thus likewise conicallyformed.

FIG. 9 also shows that the retaining ring 100, which was explained withreference to FIG. 6, can be replaced by a radial bearing collar 110 inthe first clamping surface 6, the design of the wedge surfaces inaccordance with FIG. 9 being particularly well-suited to this. Inprinciple, however, even with a first clamping surface running radiallyin accordance with FIGS. 1 to 8, it is still possible to provide aradial bearing collar in order to achieve the function of preventing thearrangement from coming completely loose.

FIG. 10 shows a set of tensioning members 120 in accordance with theinvention, consisting of four tensioning members 24 which are formed bydividing a rotationally symmetrical ring with a cross-section inaccordance with FIG. 10 a along two parallel secant sections 124, 126.Each individual tensioning member 24 has, similar to what is shown inFIG. 1, a first radial wedge surface 26, which could also be formedoutwardly conically (FIG. 9), a second, outwardly conical wedge surface28, which could also be formed radially (FIG. 9), and a third wedgesurface 30, formed inwardly conically, which could also be formedaxis-cylindrically, as has been explained in connection with FIGS. 3 and7.

A major advantage of the set of tensioning members 120 according to theinvention consists in the fact that the original ring is not dividedinto sectors along radial planes, but along parallel secant planes,which are spaced apart, so that the tensioning members can be assembledwith the minimum spacing from one another.

1. A releasable connection arrangement, with a non-positive and positivefit, for two rotationally symmetrical components, at a connection point,especially for creating a leak-proof connection between closure elementson power plant valves, the connection arrangement comprises: a firstcomponent, which has a collar projecting radially outwards with a firstclamping surface and a first bearing surface; a socket disposed at anopen end of a second component for retaining the collar by grippinground it axially; a second bearing surface formed in the socket toco-operate with the first bearing surface; a groove formed either in thefirst or in the second bearing surface to receive a seal; a secondclamping surface formed in the socket at an axial distance from thesecond bearing surface, and with a number of ring wedge-shapedtensioning members which are distributed over the circumference and aredisposed such that first wedge surfaces abut the first clamping surfaceand second wedge surfaces abut the second clamping surface; wherein anexpanding ring is provided, abutting third wedge surfaces of thetensioning members with an outer expanding surface, and tensioning meansare provided, acting between the expanding ring and one of thecomponents, with which the expanding ring can be moved axially and thetensioning members can be moved radially or radially/axially.
 2. Theconnection arrangement as claimed in claim 1, wherein the first and thesecond bearing surfaces run radially.
 3. The connection arrangement asclaimed claim 1, wherein the groove is formed in a radial portion of thefirst or second bearing surface so as to arrange the seal in parallel tothe bearing surface.
 4. The connection arrangement as claimed in claim1, wherein the first clamping surface includes a first wedge angle withthe second clamping surface, which is matched to a cone angle of theouter expanding surface in such a way that the expanding ring causesself-locking bracing of the components.
 5. The connection arrangement asclaimed in claim 1, wherein the first clamping surface runs radially andthe second clamping surface runs conically.
 6. The connectionarrangement as claimed in claim 1, wherein the first clamping surfaceruns conically and the second clamping surface runs radially.
 7. Theconnection arrangement as claimed in claim 1, wherein the first and thesecond clamping surfaces run conically.
 8. The connection arrangement asclaimed in claim 1, wherein the expanding ring is formed continuously inthe circumferential direction.
 9. The connection arrangement as claimedin claim 1, wherein the tensioning means are formed as straining screwsdistributed over the circumference.
 10. The connection arrangement asclaimed in claim 9, wherein the straining screws are located in astraining ring secured axially to the first component.
 11. Theconnection arrangement as claimed in claim 10, wherein the strainingscrews are secured to the first component by means of a circumferentialgroove and a sliding block.
 12. The connection arrangement as claimed inclaim 1, wherein the tensioning members consist of parts of a ringdivided along two parallel secant planes.
 13. The connection arrangementas claimed in claim 1, wherein the seal is formed as a metal O-ringseal.
 14. The connection arrangement as claimed in claim 1, wherein thesecond component is a high-pressure valve and the first component is alock member.
 15. The connection arrangement as claimed in claim 14,wherein the lock member is a cover lock.